// 第一题：1
const p = new Promise(resolve => {
    setTimeout(() => {
        var a = 'hello'
        resolve(a)
    }, 10)
})

p.then(a => {
    return new Promise(resolve => {
        setTimeout(() => {
            var b = 'lagou'
            resolve([a, b])
        }, 10)
    })
}).then(arr => {
    return new Promise(resolve => {
        setTimeout(() => {
            var c = 'I ❤️ U'
            arr.push(c)
            resolve(arr)
        }, 10)
    })
}).then(arr => {
    console.log(arr.join(''))
})
